So, as promised, I am going to keep videos um shorter, and that does mean by cutting them in half. So, it gives you guys a break. If you've not had a break since watching the last video, please go get a drink or or something to eat right now. Just pause it, go get yourself a drink, and then come back. Half equations. Some of you guys have covered half equations in the past, some of you haven't. Half equation is where we look at adding or removing electrons from a substance to form something else. Now, it typically goes from an ion to a solid or an ion to a gas in most scenarios. Um, you just need to know that this time we're just looking at the charges and electrons and we use those to balance in half equations. So, as you can see here, I have my sodium ion. I am adding an electron. these positives and this negative cancels and it leaves me with sodium metal. And that's basically what we've got. And down here, the same process happens. Remember that a chloride has a full outer shell. We're going to remove one of those electrons and it's going to give us Cl2, which is chlorine, which we know is in group seven. So that's why it's a diatomic molecule. Now I've written 2 Cl negative goes to Cl2 plus 2 E minus. However, some of you might be thinking it should be 2 Cl minus loses two electrons and then forms Cl2 gas. Now um I as a chemist I really don't like this. I really really don't like it. It's not necessarily wrong, but it's it it's just not right. However, it is accepted by your exam board. So, Pearson exam board do accept this as one of the answers. So, if you think that the Cl minus losing two electrons to form chlorine and so long as it's balanced makes more sense to you, then you can do this. But just know that every single time you do it, a piece of my heart chips away. So, so it's up to you, right? The next part we're going to look at is completing the following half equations. I want you guys to practice this. But before we do that, we can go through the first one together. So, potassium, it's in group one. I've got a K+ and then I'm going to form potassium metal. Very similar to sodium. It's just the period below. So, I am just going to add one electron. E to the power of negative. That's basically it. Just E minus. That's that's an electron. Mg2 plus Mg you guys can do that aluminium you can do that bromine let's have a look at a different scenario so Br is going to go to Br2 very very similar to chlorine in order to balance the charges on this side I need two electrons and I need two of these so I need two of each one of those now you can also write B Uh, but also again, part of me dies inside every time you do this. So, so I'd rather you didn't do it, but I I'll I'll take it. There you go. Um, 02 minus 2022. This is one that I kind of wanted to go through with you just because it comes up quite a few times and I don't want there to be any mistakes and I don't want you to practice any mistakes. So, I'm going to have my O 2 minus my oxide and it's going to go to O2. Now, what I'm looking at here is I've got two oxygen and one oxide. So, I'm just going to balance that straight away. Put a large two in front of that. Now, the elements or the atoms are balanced, but the charges are not. Um, yeah, there's there's two ways of doing this. Again, you can either subtract the two electrons or you can at least cheer me up and we can add two electrons to the other side, which is the most correct way of doing it and it'll make me feel better. Now the reason why this still works is if I draw a line down here like this and we count the charges over here the overall charge of the left hand side is going to be um I balanced it wrong so it's a good job I did this is going to be uh 4 minus now on this side the charge is 2 minus so you can see where I've made the mistake And now I'm going to replace that with four electrons. And that's partly why I'm glad we did this. So now on this side I have four minus. Also, you guys have probably heard me correct you or repeat this back to you, but it's 2 minus, not minus 2 or -2 or uh 2 negative or 2 minus. The number comes first and then the charge. And that's just in chemistry. But otherwise, no one really cares until you get to end level of chemistry. Right? Pause the video. Have a go at these here. And this one I want you to work out yourselves. What is hydrogen going to form at the end of it? Right. The next part, sodium chloride in H2O solution. So like I said earlier on, NaCCl is an ionic compound. We know it conducts electricity when molten or dissolved in solution. And this is the other scenario. We've looked at the molten scenario. We've heated it up. We've looked at the electrolysis. When NaCCl is dissolved into a solution, it dissociates into the following. So, I'm going to add my salt into my water. And now I'm going to write a dissociation. Salt is going to break into its metal ion. Chlorine is going to go to its chloride ion. And H2O is a combination of H+ and a hydroxide. and basically an acid and a base. So water is amphoteric. If you remember the term amphoteric, it's an acid and base. It goes on both sides here like that. The word amphoteric will come up every single year as at least a one marker. You need to know what amphoteric is. I will ask you next time I see you. H2O, H+ and O minus. So these are all the ions that are going to be in a solution. So if you have salty water, this is what you're drinking. Now I mentioned earlier there's an exception when we're looking at the electrolysis of molten and in solution. The exception is when we do an electrolysis of an aquous salt. The one exception is the product that's formed at your cathode. So at the cathode we no longer have we no longer have the sodium metal being um being reduced into its metal form or so sorry the sodium ion being reduced into its metal form. That doesn't happen. Instead the H+ this one takes precedence. This one takes priority over this. This gets left in solution. This one, this guy, he comes out in an aquous electrolysis. Hydrogen is almost always formed. As far as you guys need to know, that's the rule. Okay? So, what is formed here? Hydrogen gas. H2 G or hydrogen gas. And you can't just write hydrogen because that's this and that doesn't exist like on its own. It doesn't really make any sense. Hydrogen gas is H2. It's diatomic. So if you're stuck on this bit, this is diatomic. Um, right. The rest of it I'm pretty confident you guys can fill out. I want you guys to pause the video, have a go at completing that. One of the boxes in my videos shifted. It's the electrolyte. Remember the electrolyte is everything else. So, all of this guy or this guy, right? The next thing, the table. The table that I asked you guys to get familiar with. Now is your time to complete this. So, once you've got all of these filled out, you can now complete the table and make sure that you've got everything. Right. The next step, what I said before, NaCCl plus water is going to release all of these ions into solution. Ncl. So salty water is also known as brine. If any of you guys have ever had those tuna cans in brine, it's like salty water. That's all it is. It's just very, very, very salty water. And that's what we call brine. And the reason why I'm telling you this is because the electrolysis you look at later on is brine. During the electrolysis of brine, chloride ions form chlorine gas. Cl2. Hydrogen ions, protons form hydrogen gas. H+ goes to H2. The sodium ions and the hydroxide ions remain in solution. They stay there. They stay in solution. The next thing I want you to do is I want you to write me an ionic equation for the combination of sodium ions Na+ hydroxide and tell me what does that make? You're going to be looking at two different types of electrolysis conditions. You need to be able to identify and predict the products from each one. That's what this table is going to do. The only two scenarios you look at is molten or in solution typically of brine. So, or this is salt, but if it's in solution, it's brine. Um, I need you to tell me what is the state of sodium sodium chloride in molten in solution. The cations that are involved in that, the annions that are involved in that, the products that are formed in that. Yes, there's an extra one for the insolution one. And the energy usage, remember that the energy usage in the molten scenario is going to be higher. I want you to tell me why. This one's obviously going to be lower. So, you can just write the inverse. I don't really mind about that. Finally, the six mark question. This is something that um after going around in the classroom with you, I realized that some of you don't really have the confidence in answering like six marker type questions. So, I thought it'd be best for me to go through it with you. With this six marker, you want to break down the question into as many bullet points or as many clear points or a table, something that's easier to digest instead of just writing paragraphs. The paragraphs don't work for you and they could also cost you marks because people might miss them. The question here is compete the complete um compare the difference in sodium chloride as described below. What's the difference between a sodium chloride liquid and a sodium chloride aquous? That's all I was asking. I wanted to give you guys some extra pointers. So these are the pointers that I'm going to use. Use this structure and have a go at completing telling me what's the difference between this guy and this guy. Some of you might want to write this in a different way. So you could also write it as this. So you can have NaCCl um as a liquid and then you could also have brine over here. So brine and then you can sort it out as bonding and dissociation ability to whatever melting point um state what does it mean and the products. Okay, cool. So you could use a table like that to fill out your answers. When I'm going through in class, I don't want to see any paragraphs. I want to see this is clear as day. Keep it clear. Keep it concise. Bullet point tables. That's all I want to see for your six markers removing from now on. Echo, stop. And that's they're inputting that. Right. I'm just going to leave the video there on that one. Um again, sorry for it being a longer one. And this week's going to be a little bit tough. So, I'm going to record the next one for you. I'll see you guys soon.